users and groups

Sole reason that users exists are for access and permission, if any user would be able to bypass the OS into actual hardware the data could be accessed, encrypting the data would be ideal

UID for users, GID for groups

users not necessarily mean actual Humans, it could be

• Human users → login via shell/GUI.
• System users → service/daemon accounts (e.g., nginx, mysql).
• Root → superuser, UID 0.
• Pseudo-users → special UIDs for kernel/system tasks (e.g., nobody).

Root

• This user has access to all the files within the system

• Dangerous to work as root all the time

• That’s why superuser do or sudo is there.

• The su command stands for substitute user, if nothing specified it defaults to root

  • Downside being, you un all the commands as root, potential danger

• There is a file called the /etc/sudoers file; this file lists users who can run sudo, and can be edited with visudo

/etc/passwd and shadow

passwd - This file contains the details about the users in the system x denotes that passord is stored in shadow file

aslamcodes:x:1000:1000:Mohamed Aslam:/home/aslamcodes:/bin/bash

shadow file The password is encrypted and The numbers are related to expiry and creation date details

root:MyEPTEa$6Nonsense:15000:0:99999:7:::

passwd to change password

User management tools

useradd userdell